Adjustable antenna



Oct. 7, 1952 D. M. LISBIN ETAL 2,613,319

ADJUSTABLE ANTENNA Filed March 18, 1950 IN VENTO AS Dar/17M Iisbmfi Patented Oct. 7, 1952 --ElectricCorporation East Pittsburgh; Pay, a

corporation 0! Pennsylvania i ippiitatitn Maren-is,issogserianvo.150,488 w ,,-1,i "ceias (01. 256 -33) The invention relates tm adjustable antennas" and it particularlypeft i st0 p r a ab dipole antennas.

Adjustable antennas tages in applicationswhere a wide rangeofbper atlng frequencies argues-ag inst the use of a single fixed antennain theintere'stof good reca ti'on, and where'theuse of a number-"of" fixed antennas is impractical: For most practicalposes, adjustable antennas. provide the only means for tuning tliantenna at" every operating frequency for optimum gain.

In the field of televisionthe use I of adjustable antennas is particuiariy advantageous owing to the extremely wide range of operating frequen cies extending over several octaves Structures have been proposed lawman telescoped sections or similar expedients have been employed rat-' length" adjustment; However, over a range of" several octaves a comparatively large number or sections must be used, increasing thethicknessj 0f the antennaand creating a discontinuity of considerable proportions at" the eraser the outer sleeve when, for example, o'ii'lyfior'ie' section is extended. M

Other expedients in general have proven objectionable on the score of low antenna gain. In regions of low signal strength, especially where the antenna is designed for indoor-use,- this is a fatal objection. Since the design of-indoor'a'n tennas requires careful considerationof both appearance and convenience; it has not been possible heretofore to provide such" an antenna with the high gain desirablefoncle ar reception. I

It is, therefore, an object of this invention to provide a high gain adjustable. antenna of convenient size, attractive appearance and novel construction.

It is another object or this invention to provide an adjustable antenna small enough to permit portable use.

Yet another object of this invention is to provide an adjustable antenna requiring little time and effort to adjust by even the least skilled user.

A further object of the invention is to provide, in an adjustable antenna, means providing a continuous path for electric current from its tip to the point of energy transfer, irrespective of the position of adjustment.

A still further object is to provide an antenna having one or more arm of adjustable length and of uniformly varying cross section.

These and other objects and advantages will be apparent from the following description in which reference is had to the accompanying possess decided advan tion. I i a 1, In thedrawing:

drawingillustrating enga ements. the inve -Fi"g.- 1 1 is. a front; elevation of aidipoleiantenna according to the invention;

Figs. 2, 3 and 4" are alfront elevation, aplan view and a side elevation;v respectively, showing thesameantenna in closed positionfiandv 5* is an enlarged longitudinalcrosssection of thecentralportion of the antenna shown in the preceding-figuresk.

'Referring'torthedrawing indetailzi- As best seenin' Fig. .1,the. antenna is of the dipol'e type' comprising. two arms ill, l0 shown,

for clarity of illustration, .in :fully extended and.

partially extended positions,v-respectively;' Each arm: is formed by a volutewcon'ductive strip'or spiral of stainless steel or similarspring material. Inthe' closed position showninFigs. 2 to 4' the coils fit closely within a dielectric sleeve. to

which they are fastenedz Plastic :knobs 12,42" are fixed to the ends o fthe-arms Ml; l0, respec-" tively. a

The sleeve" H is' supported by a plasticframe: l3, which, for economy of 'm'anufa'cture, comprises two symmetrical sections lila, [31) bolted together along the line- I 4' by nuts and bolts I5.

The frame assembly stands on: a'round ba'se illi."

AZ calibrated chart 'l'l relating frequencyto proper as shown in Fig. '5': A groove 23 along frame section13baccommodatesthec lb qg z.

The" arrangement-of the volutestrip-withiri the sleevei's illustrated in detail in Fig; S-Which also shows means for facilitating adjustment of the arms l0, ID to at least approximately equal length. As shown, the first loop or turn of each coil is held by pin 20 or 20'. The aforementioned loops are electrically insulated but mechanically coupled together by bars 2 la, 2 lb, pivoted thereto at 22a, 22a and 22b, 22?), respectively, in such manner that any extension or retraction of arm It], or It, will tend to produce a corresponding extension or retraction of arm Ill, or III. I

To adjust the antenna, it is necessary only to pull out the coils l0, I0 to the desired length, as shown in Fig. l, and turn knobs I2 and I2 counterclockwise, i. e., in a direction tending to expand the turns of the coil, thereby locking the coil in position. To retract the arms or vary their length, the knobs may be turned clockwise,

hence in a direction tending to contract the turns, whereupon the desired adjustment may be made. This efiect is due to the fact that the volute strip or coil possesses two modes of expansion, one tending to produce axial and the other radial motion. In th arrangement shown, these tendencies may be made mutually opposing. Thus, by turning the knobs l2, I2 until the turns'of the coils press against one another and, ultimately, against the fixed sleeve II, the binding efi'ect produced by the outward pressure of the spirals prevents further lateral expansion.

In order to adjust both arms to substantially the same size, the operator simply extends one of the arms I 0, I to the desired length, loosens the the bars Zla. 2Ib. The operator will be able to 3. An adjustable antenna comprising a support, a pair of flexible volute conductors extending from said support in difierent directions, each of said conductors having one end anchored to said support, each of said conductors having each turn in overlapping contact with the next succeeding'turn, andlocking means for adjustably maintaining the other end of each of said conductors in axially spaced relation to said support. '4. An adjustable antenna comprising a support including a rigid sleeve with two open ends, a pair of flexible volute conductors each having its outermost turn secured to the inside of said sleeve adjacent a respective one of said open ends, each of said conductors having each turn in overlapping contact with the next succeeding turn, and locking means for adjustably maintaining the innermost turn of each of said conductors in axially I spaced relation to said sleeve.

determine when this length has been reached bya marked restoring force opposing any motion around that point. It will be understood, however,

that the bars Zia, 2") may be omitted if such.

automatic adjustment is deemed unnecessary, and that notwithstandingthe presence of these bars the arms l0, l0 may also be set at materially dif ferent lengths, as shown in Fig. 1.

It will be noted that the improved antenna according to the invention presents at all times clos'ed,.in accordance with the objects outlinedhereinabove, a portable, high gain adjustable antenna inwhich all discontinuities have been substantially eliminated. 'I'heinvention is, of course. not limited to the specific form described and illustrated but may be embodied in a variety of modes of realization without exceeding its scope as defined in the appended claims.

We claim: v

1. ;In an adjustable antenna, in combination, a support including a rigid sleeve and a volute strip of resilient conductive material. each turn of which is an overlapping contact with the next succeeding turn, said strip having its outermost. turn bearing against the inside of said sleeve and anchored to said support, said strip being extendible and capable of fixation in any extended position by rotating its free end in a sense tending to expand the turnsof the strip.

Y 2. The combination according to claim 1 wherein said strip is provided with a knob at its free end.

5. An adjustable antenna comprising a support including arigid sleeve with two open ends, and a pair of volute strips of resilient conductive material each having its outermost turn bearing against the insideof said sleeve, adjacent a respectiveone of said open ends, and anchored to said ,support, saidstrips having each turn in overlapping contact with the next succeeding turn, said strips being extendible in opposite directionsand capable of fixation in any extended position by rotating their free ends in a sense tending to expand the turns of the respectivestrip.

6. An antenna according to claim 5, comprising ing to place the free end of the corresponding,

strip in a position related to that of the free end of the other strip.

DAVID M. LISBIN. IRA BIVANS.

REFERENCES CITED The following references are of record in the "file .of this patent:

UNITED STATES PATENTS 

